This invention relates to a diagnostic instrument for communicating with and providing diagnostic information on instruments such as gauges, indicating lights, numeric displays, and switches in the cab or driver area of a mobile vehicle and the algorithm for assisting in the communication and display of the diagnostic information. The instrument makes use of existing industry standard or proprietary communication protocols and a vehicle mounted controlled area network to communicate with and provide diagnostic information on the vehicle instruments. This application is related to U.S. Pat. No. 6,263,269 that is assigned to inventor""s assignee.
At a simple level, communication between two agents may be kept physically separated from communications occurring among other agents. Where two or more signals do not use the same physical space, there is no need to separate the signals in time or in carrier wave frequency. Such a communications regime is sometimes termed physical division multiplexing although the term multiplexing is usually reserved to techniques for applying multiple signals to a single medium or physical space. So-called physical division multiplexing describes how motor vehicles have been traditionally wired. The use of separate dedicated wires to connect each switch and lamp is a type of physical division multiplexing. Obviously, physical division multiplexing, while simple in concept, results in the use of many wires (the classical motor vehicle electrical harness), which are difficult to install during manufacturing and problematic to maintain in the field.
Arrangements allowing a number of agents to communicate over a common physical layer or medium offer much greater physical simplicity. Intelligible communication between two or more devices among a greater plurality of devices, all over a common medium, depends upon the communicating devices being able to distinguish, and understand, messages directed to them from other messages which they receive, but which are not intended for them. The process of distinguishing messages depends upon the transmitter of the message applying some attribute to the message that identifies it to the intended recipient. In human conversation, most people readily distinguish speech directed to them from interfering cross-talk in a crowd by the distinctive aspects of the voice of the person addressing them. Where the members of the group are electrical components, the problem still involves identification of a distinguishing attribute of the signal. Appropriate attributes for signals take a number of forms.
A line communicating a signal from a remote switch to a lamp to turn on or off (by having a second switch, local to the lamp, change states to control connection of the lamp between a power bus and ground) cycles only rarely. In a typical trip such a change in state occurs only once or twice, if at all. Where such a line is not intended to provide power to the lamp, and simply indicates changes in state for the local switch controlling the lamp, the line will have the capacity to handle far more data than the occasional indications to turn a lamp on and off. The objective of maintaining simplicity in manufacturing and maintenance are preferably met by allowing communication among a number of components to occur in a single medium, or at least as few communication lines as possible. The line used to connect switch and lamp could interconnect a number of components, carrying messages between any grouping of elements connected to the line when not required to carry an instruction to a lamp to turn on. One way of achieving this objective is a communications regime that divides time into slots during which particular combinations of components have use of a signaling line. Such methods are well known in the art and are examples of time division multiplexing (TDM). In motor vehicles, time division and related multiplexing techniques offer substantial simplification in physical layer required to support the control of vehicle vocations.
Rigid time division multiplexed communications appear to interleave data signals into a single serial signal over a single physical medium. Multiplexed communication systems also provide the reverse function (de-multiplexing) of dividing the single signal into multiple, non-synchronous digital signals. Where demands on the capacity of the data transmission medium are not especially heavy, any unit may be allowed to claim the medium provided collision detection is provided for and other indicia, such as address headers, indicate the signal""s destination.
As applied to motor vehicles, multiplexed communications over serial data paths are an effective technique for reducing the number of dedicated communication paths between the numerous switches, sensors, devices and gauges installed on the vehicles. With each increase in the number and variety of accessories and functions installed on each vehicle, the benefits of using a single, multiplexed communication serial link for passing instructions to and receiving information from vehicle devices as diverse as running lights and rear axle temperature sensors becomes greater. Multiplexing the signals to and from local controllers and switches for vehicle systems promises greater physical simplicity through displacing much of the vehicle wiring harness, reducing manufacturing costs, facilitating vehicle electrical load management, and enhancing system reliability.
The specific manner of implementing multiplexed communications is outside the scope of the present invention, which applies a defined protocol, the SAE J1939 protocol. Additionally, proprietary protocols may be used although over a network similar to as described here. The development by the Society of Automotive Engineers of the J1939 series of standards for multiplexed communications testifies to the progress in the application of multiplexed communications to vehicles. Standards have been or are being developed relating the communication path, transmission collision detection, diagnostic ports and data protocols, among other topics. The J1939 protocol provides an open protocol and definition of the performance requirements of the medium of the physical layer, but also allows for development of proprietary protocols. The SAE J1939 protocol is a specialized application of a controlled area network (CAN) and may be readily implemented utilizing commercial integrated circuits such as the C167 Integrated Circuit from Siemens of Germany.
A serial communications system utilizing a multiplexing regime can link several remote digital controllers positioned around a vehicle with an electrical system controller (ESC) for two way communication. Remote digital controllers are addressable, allowing them to respond to signals intended for them initialize particular functions. As described above the controllers for the vehicle instruments may be remote digital controllers. They may also include programming that allows the device to react to local conditions as well as condition indicating signals provided the controller. The ESC may pass requests and instructions received for operations of certain devices, addressed to the correct remote controller, in a fashion to condition the timing and duration of the responses to requests to better manage overall vehicle electrical load.
Electronic modules and components that communicate under protocols such as J1939 may require diagnosis or troubleshooting. In the prior art, such modules and components were diagnosed and electrically examined using an instrument that translated data to hexadecimal numbers that were then interpreted by an engineer using a calculator. Messages were constructed in the same time consuming manner. Diagnosis of components that communicate under J1939 or other similar protocols was not user friendly and in no case included a mock simulated gauge cluster or vehicle instrument panel for easy relation of actual gauge cluster and vehicle instrument panel diagnosis.
What is needed and does not exist in the prior art is a user-friendly vehicle controlled area network diagnostic instrument for diagnosing electronic modules and components that communicate under J1939 or similar communication protocols and includes a mock simulated gauge cluster or vehicle instrument panel for easy relation of actual gauge cluster and vehicle instrument panel diagnosis.
An object of the invention is to provide is a user-friendly vehicle controlled area network diagnostic instrument for diagnosing electronic modules and components that communicate under J1939 or similar communication protocols. A second object of the invention is to provide for a diagnostic tool for mobile vehicle applications that includes a mock simulated gauge cluster or vehicle instrument panel for easy relation of actual gauge cluster and vehicle instrument panel diagnosis.
The controlled area network diagnostic instrument (CANDI) and computer algorithm for programming computers to allow vehicle instrument diagnosis of this invention satisfies all the objects of the invention and others not mentioned. The diagnostic tool of this invention may be a computer processor either portable or fixed with graphics display such as a monitor. The processor has a cable and adapter to plug or hook into diagnostic connector engaged to a common data bus of the vehicle, which may be a serial data bus or link. The serial data bus or link is made in accordance with J1939, other industry electronic communication standards, or proprietary standards. The processor has a display that is programmed to graphically show a mock or simulated gauge cluster or vehicle instrument panel in that has the same appearance as a real vehicle gauge cluster or vehicle instrument panel. A vehicle subject to the diagnostics of CANDI will have a real vehicle gauge cluster of the vehicle electrically engaged to the common data bus, as will be an Electrical System Controller (ESC). The ESC controls the flow of communication over the data bus. When connected to the diagnostic connector, the CANDI takes or mines data off of the data bus and converts it into human readable form. This may take the form of conventional gauges, warning lights, switch status, or LCD displays shown via computer graphics on the processor""s monitor. This may take the form of a mock or simulated gauge cluster or vehicle instrument panel. Where there are no changes in data, the mock display appears like a picture of the real gauge cluster or vehicle instrument panel. Where the mined data changes, the CANDI converted human readable form will make the mock display appear like a moving picture of the real display. Likewise, CANDI may take the human readable data and put it on the data bus. This may result in the ESC or other remote interface modules driving or directing the movement of actual gauges, switches, warning lights, or LCD displays to vary their display. This human readable data may be input into the CANDI processor by use of a computer mouse or other pointer to change the position of switches and gauge needles shown on the mock display or use of the key pad to input numeric into selected numeric indicators on the mock display.
Additional effects, features and advantages will be apparent in the written description that follows.